SOMEONE I ADORE commented casually to me the other day that he didn't need to plan for his retirement because he wasn't going to live that long. When I protested, he looked at me evenly and said, "Look, it's just true. No sense behaving otherwise."

He'd had open-heart surgery in his late teens that saved him from dying at the time but left him without the prospect of an old age. As if recalling some obscure spec from a hardware manual, he explained, "After my surgery, I got this little pamphlet--it was called 'your new heart' or something like that--and it said I shouldn't expect to live past 65." I tried to imagine what it would be like to know something irreversible had happened to my body that meant it couldn't possibly function for as long as other people's. It felt weird, but unexpectedly comforting. At least I would know what to expect.

It's at moments like this--realizing my sweet, vivacious companion would never be an old man--when I remember how much of science is founded on a wish to escape our physical limitations. Rationalism is, after all, a direct response to religion. And religion is somewhat notorious for attempting to solve the problem of mortality by positing a spiritual realm where something essential about us continues to live, usually in some altered (and better) form. Science may try to explain death as a biological and evolutionary process, but I'm not convinced that these explanations serve a purpose that's fundamentally different from those offered by mystics and Dharma-addled hippies.

Timothy Taylor, a British anthropologist, has written a book (coming out in July) about the idea that humans "invented death" by creating elaborate rituals around it. Funerals, burying the dead and sending flowers, he argues, are all ways that humans cope with the horror of losing their loved ones. As his tales about sacrifice among early humans unwind, it becomes clear that Taylor himself is engaging in a ritual of his own: that of anthropology, in which a dispassionate scientist makes sense of death by placing it in such a broad historical context that it no longer feels personal or tragic.

A similar urge overcame me when my mother was dying. As her unconscious body lay between banks of computers, I took comfort in talking to the least socially adept of her surgeons, a biogeek whose affectless interest in her reminded me of a hacker looking at insecure lines of code. He told me about weird, cutting-edge surgical techniques he might use on her and the pieces of technology he wished he had to diagnose her failing heart. He was precisely the kind of doctor you always hear people criticizing: he had absolutely no "human" touch, which is to say that he didn't take my hand and try to empathize with me at all. But fuck that sweet-talking bullshit. I'd rather face death with a nerd than a priest.

Sometimes, of course, science actually saves people from dying, which sensitivity and worship never do. For the past couple of weeks, a total artificial heart called the Cardiowest has been capturing headlines because the FDA is approving it for use as a "bridge to transplant," or a temporary stopgap measure for patients hoping to score somebody else's heart. The device will be the first in widespread use that completely replaces the human organ. Others have only aided with the functionality of one ventricle or the other. It's the dream of religion, realized by science: We no longer need our hearts to live; we transcend our flesh. At least, we transcend it for a little while, as long as we don't get infections from having machines implanted in us, or start bleeding uncontrollably from all the blood thinners.

My adored friend, who anticipates his death with such calm, has a cyborg heart. One valve is from an animal; the rest of the thing is all his, although it was modded by surgeons who sewed up a hole in it when he was an infant. A perfectly straight scar running down his chest means he'll never forget his mortality. But without high-tech medicine, he never would have lived long enough for us to meet. Sometimes I get a creepy, almost mystical feeling when I'm with him, as if I'm talking to a ghost about building the perfect Linux machine. Do the undead need to learn awk and korn shell?

Then I remember that this is biology, after all. His heart is just a machine, and luckily somebody figured out how to fix it before the thing crashed. Certainly, there's a ritualistic, spell-casting aspect to medicine, but the shit really works. Still, it doesn't prepare us for death anymore than prayer does. It just comforts us while we wait.